Printing of polishing pads

ABSTRACT

A polishing pad includes a flexible substrate and a polymeric polishing layer that has a repeatable pattern of polymeric asperities that are manufactured by printing, according to a gravure printing process or a screen printing process.

[0001] This application claims the benefit of U.S. Provisional PatentApplication No. 60/176,827 filed on Jan. 19, 2000 and U.S. ProvisionalPatent Application No. 60/178,951 filed on Feb. 1, 2000.

[0002] The present invention relates to polishing pads for polishingdielectric/metal composites, semiconductors, integrated circuits andmetal substrates, especially copper and tungsten as preferredsubstrates.

[0003] Polishing generally consists of the controlled wear of aninitially rough surface to produce a smooth specular finished surface.This is accomplished by rubbing a polishing pad against the surface ofthe article to be polished in a repetitive, regular motion while asolution containing a suspension of fine particles, typically a slurry,is present at the interface between the polishing pad and the workpiece. Commonly employed pads are made by impregnating non-woven fiberssuch as polyester with a urethane or are formed from filled castpolyurethanes. The polishing contact area of these pads can be affectedby texturing the surface of the pads, grooving the pads, embossing orperforating the pads. s shown in Cook et al, U.S. Pat. No. 5,489,233issued Feb. 6, 1996, pads having a macrotexture and microtexture can beformed. Such pads can be produced by molding, pressing, embossing,casting, cutting, sintering or by photolithographic means.

[0004] Typically, polishing pads are made in a batch process where onepad is produced and then another which often results in significantbatch to batch variability. This variability in pads is detrimental tosemiconductor wafer manufacturing since it leads to polishing processvariability and ultimately yield losses. A pad manufacturing process isneeded that forms a pad having a uniform surface, and in particular, acontinuous process is needed that forms a sheet having a uniformsurface. From such a sheet, either individual polishing pads can be cutor the sheet can be left intact to form roll or belt type pads for nextgeneration polishing tools.

[0005] The invention relates to polishing pads and a process for makingpolishing pads by printing.

[0006] Embodiments of the invention will now be described by way ofexample with reference to the accompanying drawings, according to which:

[0007]FIG. 1 is a perspective view of gravure printing that can be usedto form the polishing pads of this invention.

[0008]FIG. 2 is a perspective view of screen printing that can be usedto form the polishing pads of this invention.

[0009] The invention is directed to polishing pads and a process,preferably a continuous process, for making these polishing pads;wherein the pads have a flexible base substrate; and firmly adhered tothe base substrate a hydrophilic polymeric polishing layer having apattern of polymeric asperities formed by printing. According to oneembodiment, printing includes a process of gravure printing. Accordingto another embodiment, printing includes a process of screen printing.An embodiment of a polishing pad without abrasive particles is formed bythe process of printing, and perform polishing in combination withparticulate containing slurries. Another embodiment of a polishing padincludes abrasive particles that may be incorporated into the pad by theprocess of printing. The pad with abrasives perform polishing in whichthe pad is used with a reactive polishing liquid that is withoutabrasives.

[0010] The polishing pad made by the process of this invention has apolishing layer of a hydrophilic polymer having a pattern of polymericasperities formed by gravure printing or screen printing. The printingprocess forms a repeatable surface pattern of polymeric asperities thathave a controlled particle size, pattern, geometry and height. Prior artmethods for forming patterns on polishing pads include molding,sintering, pressing, embossing, casting or cutting. These methods areeither not suitable for manufacture of continuous pads or not repeatablewith any great accuracy. The use of a printing process, for example, agravure or screen printing process, provides an accurate repeatablesurface area pattern that is applied as a polishing layer of a polishingpad. Gravure printing is best suited for the formation of a polishinglayer having a pattern of precise, low-profile polymeric asperities.Screen printing is best suited for the formation of a polishing layerhaving a pattern of higher aspect polymeric asperities. These polymericasperities are the numerous peaks of polymeric material which may be ofvarious heights and shapes that forrn the polishing layer which areapplied by the printing process on the flexible substrate. The shapes,heights and area pattern of the polymeric asperities are repeatablyapplied with minimized variation, due to the fixed pattern on thesurface of the gravure printing roll or the fixed area pattern of ascreen used in the screen printing process.

[0011]FIG. 1 discloses a gravure printing apparatus and process formanufacture of a polishing layer onto a flexible substrate on whichprinting is performed. A rotogravure cylinder 1 is mounted on a typicalrotogravure printing machine. The cylinder 1 has an outer peripheralsurface 2 in which the pattern of the polishing layer is etched. Thefixed area pattern 3, is etched on the entire surface 2 of the cylinder1. For simplicity, only a small portion of the pattern is shown. Injuxtaposed spaced relationship to cylinder 1 is impression roller 4which is in intimate contact with cylinder 1 during the printingprocess. Cylinder 1 is partially immersed in a tray 7 containing apolymeric material (polymer solution or dispersion or a liquid lowmolecular weight polymer) 8 and is in frictional engagement with adoctor blade 6, which wipes off the excess polymeric solution ordispersion and returns this excess to the tray 7.

[0012] A flexible base substrate sheet 5 that is to be printed passesbetween the cylinder 1 and impression roller 4 and is maintained in firmintimate contact with cylinder 1 by properly adjusting roller 4. Thisprinting process is advantageous since the depth of the layer ofpolymeric material and the area pattern of peaks and valleys arecontinuously applied and repeated with great accuracy, due to the fixeddimensions of the etched pattern on the cylinder 1. The intimate contactof the substrate sheet 5 and the cylinder 1 is very important in orderto assure the transfer of all available polymeric material to thesurface of the substrate being printed. The impression roller 4 mustmaintain a constant force and pressure on the cylinder 1 with thesubstrate 5 in order to assure the desired result. Typically a force ofabout 150 psi (pounds per square inch) is maintained but depending onthe materials used a force in the range of 50-300 psi can be used. Afterbeing printed the polymeric material on the substrate sheet is cured,for example, by being passed through a curing zone 13, FIG. 2, that is aheating oven (typically, using temperatures of 75-150° C.) but radiationcan be used such as UV radiation, to cure the polymeric material printedonto the substrate. The resulting substrate with the cured patternedcoating then is wound up and can be cut into individual polishing padsor provides a continuous polishing belt form of polishing pad.

[0013] Further details of rotogravure printing and the construction ofcylinders used in rotogravure printing are known from Bardin, U.S. Pat.No. 4,197,798, hereby incorporated by reference.

[0014]FIG. 2 discloses a screen printing apparatus and process that canbe used to form the polishing pads of this invention. Screen printing isperformed by dispensing the polymeric material, with or without abrasiveparticles in suspension, through an open screen. The fixed area patternof the screen defines the repeatable area pattern of the polymericmaterial that is dispensed through the area pattern of the screen. Aflexible base sheet substrate 9 is fed from a roll and is in juxtaposedposition to a screen template 10 being fed from a roll. A polymericmaterial (which can be in the form of a solution or dispersion or aliquid low molecular weight polymer) 11 is placed in contact with thetemplate 10 and forced into and through the pattern of the template 10by doctor blade 12 and into contact with the substrate 9. The template10, the polymeric material 11 on the substrate 9 are passed through acuring zone 13 which may be an oven (typically, using temperatures of75-150° C.) or for example UV radiation to cure the polymeric materialon the substrate. The template 10 is simply removed after curing andwound up. The resulting substrate with the cured patterned coating 14then is wound up and can be cut into individual polishing pads or intopolishing belts.

[0015] Manufacturing of polishing pads by either gravure or screenprinting techniques enables a continuous polishing surface with a singlecontinuous region, or a region divided into discrete regions ofpolishing surface to be defined separated by channels or gapstherebetween. The shape of these discrete regions may be any geometry(circular, square, triangular, polygonal, etc.) but hexagons arepreferred because of ease of achieving high-density, regular packing.Typical dimensions of these regions are as follows: Feature DiscreteArea Discrete Area Channel Dimension Diameter (mm) Thickness (mm) Width(mm) Range 1-25 0.1-10 0.1-15 Preferred Range 3-15 0.3-3 0.3-3 MostPreferred 5-10 0.5-2 0.5-2 Range

[0016] These discrete regions are advantageous for the followingreasons:

[0017] After a polishing pad is formed by screen printing, it isnecessary to remove moisture from the screened formulation. If there isa continuous coating or layer, unacceptable cracking of the coating orlayer occurs. This is eliminated by forming discrete regions.

[0018] The channels surrounding the discrete regions facilitate slurry(or reactive liquid) transport across the pad surface and the subsequentremoval of polishing debris in the polishing operation.

[0019] The flexible base substrates used in this invention can comprisea single layer or multiple layers and can comprise of a combination oflayers that are bonded together. The substrate is preferably a flexibleweb capable of being pulled from a roll or easily wound into a roll. Onepreferred substrate is a non-corrosive metal, such as aluminum orstainless steel. Other preferred base substrates are plastics, such asengineering plastics, for example a polyamide, polyimide, and/orpolyester, particularly “PET” poly(ethylene terephthalate).

[0020] The flexible base substrate of the present invention preferablyhas a thickness of about 0.1-10 millimeters. In a preferred embodiment,the support layer has a thickness of less than 5 millimeters, morepreferably less than 2 millimeters. yet more preferably less than 1millimeter.

[0021] The polishing layer of the polishing pad of this inventioncomprises a hydrophilic polymeric material that optionally may be filledwith abrasive particles. The polishing layer preferably has: (i) adensity greater than 0.5 g/cm³; (ii). a critical surface tension greaterthan or equal to 34 milliNewtons per meter; (iii) a tensile modulus of0.02 to 5.00 GigaPascals; (iv) a ratio of tensile modulus at 30° C. totensile modulus at 60° C. of 1.0 to 2.5; (v) a hardness of 25 to 80Shore D; (vi) a yield stress of 300-6000 psi (2.1-41.4 MegaPascal);(vii) a tensile strength of 1000 to 15,000 psi (7-105 MegaPascal); and(viii) an elongation to break up to 500%. In a preferred embodiment, thepolishing layer farther comprises a plurality of soft domains and harddomains.

[0022] Preferred hydrophilic polymeric materials used to provide apolishing layer having a critical surface tension greater than or equalto 34 milliNewtons per meter, more preferably greater than or equal to37 and most preferably greater than or equal to 40 milliNewtons permeter are shown below in comparison other conventional polymers.Critical surface tension defines the wettability of a solid surface bynoting the lowest surface tension a liquid can have and still exhibit acontact angle greater than zero degrees on that solid. Thus, polymerswith higher critical surface tensions are more readily wet and aretherefore more hydrophilic. Critical Surface Polymer Tension (mN/m)Polytetrafluoroethylene 19 Polydimethylsiloxane 24 Silicone Rubber 24Polybutadiene 31 Polyethylene 31 Polystyrene 33 Polypropylene 34Polyester 39-42 Polyacrylamide 35-40 Polyvinyl alcohol 37 Polymethylmethacrylate 39 Polyvinyl chloride 39 Polysulfone 41 Nylon 6 42Polyurethane 45 Polycarbonate 45

[0023] In one preferred embodiment, the polishing layer of the pad isderived from one of the following:

[0024] 1. an acrylated urethane;

[0025] 2. an acrylated epoxy;

[0026] 3. an ethylenically unsaturated organic compound having acarboxyl, benzyl, or amide functionality;

[0027] 4. an aminoplast derivative having a pendant unsaturated carbonylgroup;

[0028] 5. an isocyanurate derivative having at least one pendantacrylate group;

[0029] 6. a vinyl ether,

[0030] 7. a urethane

[0031] 8. a polyacrylamide

[0032] 9. an ethylene/ester copolymer or an acid derivative thereof;

[0033] 10. a polyvinyl alcohol;

[0034] 11. a polymethyl methacrylate;

[0035] 12. a polysulfone;

[0036] 13. an polyamide;

[0037] 14. a polycarbonate;

[0038] 15. a polyvinyl chloride;

[0039] 16. an epoxy;

[0040] 17. a copolymer of the above; or

[0041] 18. a combination of any of the above.

[0042] In another preferred embodiment of this invention, the polishinglayer material comprises: (1) a plurality of rigid domains which resistsplastic flow during polishing; and (2) a plurality of less rigid domainswhich are less resistant to plastic flow during polishing. Thiscombination of properties provides a dual mechanism which has been foundto be particularly advantageous in the polishing of silicon dioxide andmetal. The hard domains tend to cause the protrusion to rigorouslyengage the polishing interface, whereas the soft domains tend to enhancepolishing interaction between the protrusion and the substrate surfacebeing polished.

[0043] The rigid phase size in any dimension (height, width or length)is preferably less than 100 microns, more preferably less than 50microns, yet more preferably less than 25 microns and most preferablyless than 10 microns. Similarly the non-rigid phase is also preferablyless than 100 microns, more preferably less than 50 microns, morepreferably less than 25 microns and most preferably less than 10microns. Preferred dual phase materials include polyurethane polymershaving a soft segment (which provides the non-rigid phase) and a hardsegment (which provides the rigid phase). The domains are producedduring the forming of the polishing layer by a phase separation, due toincompatibility between the two (hard and soft) polymer segments.

[0044] Other polymers having hard and soft segments could also beappropriate, including ethylene copolymers, copolyester, blockcopolymers, polysulfones copolymers and acrylic copolymers. Hard andsoft domains within the pad material can also be created: (1) by hardand soft segments along a polymer backbone; (2) by crystalline regionsand non-crystalline regions within the pad material; (3) by alloying ahard polymer with a soft polymer; or (4) by combining a polymer with anorganic or inorganic filler. Useful compositions include copolymers,polymer blends interpenetrating polymer networks and the like.

[0045] In a another embodiment of this invention, thin polishing layersless than 200 microns, more preferably less than 100 microns and yetmore preferably less than 50 microns and comprise a random surfacetexture comprising pores and/or micro-voids of varying sizes anddimensions can be formed.

[0046] The combination of a thin base layer and a thin polishing layercan provide ultra high performance polishing, due to a more precise andpredictable polishing interaction when a rigid support presses the thinpolishing pad against (and the pad is moved in relation to) a substrateto be polished. This polishing pad can be manufactured to very tighttolerances and (together with the rigid support) can provide predictablecompressibility and planarization length. “Planarization length” isintended to mean the span across the surface of a polishing pad whichlies substantially in a single plane and remains in a single planeduring polishing, such that as tall peaks are polished, peaks of lesserheight do not polish unless or until the taller peak is diminished tothe height of the shorter peak.

[0047] The polishing pads formed according to this invention have apolishing layer that is substantially free of macro-defects.“Macro-defects” are intended to mean burrs or other protrusions from thepolishing surface of the pad which have a dimension (either width,height or length) of greater than 25 microns. Macro-defects should notbe confused with “micro-asperities.” Micro-asperities are intended tomean burrs or other protrusions from the polishing surface of the padwhich have a dimension (either width, height or length) of less than 10microns. It has been surprisingly discovered that micro-asperities aregenerally advantageous in ultra precision polishing, particularly in themanufacture of semi-conductor devices, and in a preferred embodiment,the polishing layer provides a large number of micro-asperities at thepolishing interface.

[0048] To obtain adequate adhesion of the hydrophilic polymer polishinglayer to the flexible base substrate, the substrate may require a primeror an adhesion promoter.

[0049] Conventional polishing compositions or slurries used with thepolishing pads of this invention to polish dielectric metal composites,semiconductors or integrated circuits generally contain finely dividedabrasive particles in an aqueous slurry or dispersion. The part orsubstrate that is to be polished is bathed or rinsed in the compositionwhile the polishing pad is pressed against the substrate and the pad andsubstrate are moved relative to each other. The abrasive particles arepressed against the substrate under a load and the lateral motion of thepad causes the abrasive particles to move across the surface of thesubstrate resulting in wear and volumetric removal of the surface of thesubstrate. The rate of removal is determined by the amount of pressureapplied, the velocity of the polishing pad and the chemical activity ofthe abrasive particles.

[0050] Polishing rates can be increased by adding components to thepolishing composition which by themselves are corrosive to thesubstrate. When used together with abrasive particles, substantiallyhigher polishing rates can be achieved. This process is termedchemical-mechanical polishing (CMP) and is a preferred technique used topolish semiconductors and semiconductor devices, particularly integratedcircuits. Additives can be introduced to the polishing compositions toaccelerate the dissolution of a metal component of the substrate such asa dielectric/metal composite structure, for example an integratedcircuit. The purpose of this is to preferentially remove the metalportion of the circuit so that the resulting surface becomes coplanarwith an insulating or dielectric feature, typically composed of silicondioxide. This process is termed planarization. Oxidizing agents, such ashydrogen peroxide, also can be added to the polishing compositions usedfor CMP to convert a metal surface into an oxide that then is subject toCMP.

[0051] Typical polishing compositions used for CMP of semiconductors,integrated circuits wafers and the like are disclosed in Brancaleoni etal, U.S. Pat. No. 5,264,010 issued Nov. 23, 1993; Cook et al, U.S. Pat.No. 5,382,272 issued Jan. 17, 1995; Brancaleoni et al, U.S. Pat. No.5,476,606 issued Dec. 19, 1995 and Wang et al, U.S. Pat. No. 5,693,239issued Dec. 2, 1997. While these are excellent polishing compositions,it would be desirable to have a composition that would remove anextremely thin layer without scratching of the surface and can be usedfor polishing substrates for semiconductor devices that require highplanarization.

[0052] These conventional polishing compositions typically are slurriesand the abrasive particles therein have a surface area of about 40-430m²/g, and mean aggregate size of less than 500 nm and a force sufficientto repel and overcome van der Walls forces between the particles. Thesurface area of the particles is measured by the nitrogen adsorptionmethod of S. Brunaure, P. H. Emmet, and I. Teller, J. Am. ChemicalSociety, Vol. 60, page 309 (1938). The particles may comprise between0.5% -55% by weight of the slurry depending on the degree of abrasionrequired.

[0053] The abrasive particles can be primary particles having a meansize range of 25-500 nm or a mixture of primary particles andagglomerated smaller particles having a mean size range of 25-500 nm. Ina preferred embodiment of the method of this invention, the abrasiveparticles have a mean size ranging of 25 and 500 nm. Typically usefulabrasive particles are alumina, ceria, diamond, silica, titania and thelike. These particles and agglomerates can be encapsulated and suspendedsatisfactorily so that, while maintaining the hardness, the possibilityof scratches to the surface being polished is mininal.

[0054] It is preferred that the particles in the slurry not settle andnot be agglomerated. However, it is understood that depending on thepercentage of primary particles and agglomerated particles, theparticles in the slurry may settle and require redispersion bymechanical means such as mixing.

[0055] Oxidizers can be added to these slurries in amounts of about0.01-10.0% by weight, based on the weight of the slurry. A wide varietyof oxidizers can be used such as oxidizing metal salts, oxidizing metalcomplexes, iron salts such as nitrates, sulfates, potassium ferricyanideand the like, aluminum salts, sodium salts, potassium salts, ammoniumsalts, quaternary ammonium salts, phosphonium salts, peroxides,chlorates, perchlorates, iodates, periodates, permanganates, persulfatesand mixtures thereof. These oxidizers also can be added to polishingcompositions of this invention wherein colloidal sulfur is the primarypolishing constituent and other abrasives are not present.

[0056] Organic additives can be used in the slurries in concentrationsof about 0.01-10% by weight, based on the weight of the slurry. Theseadditives function as an encapsulating, suspending means for theparticles, which are present, so that the possibility of scratches isminimal in spite of the hardness of the small particles. Alternatively,these additives may improve the surface quality by adsorbing on thepolished surface as well as protecting the oxide surface and associatedbarrier layer during polishing. These organic additives may also beincorporated to improve the global wafer uniformity of the surface ofthe semiconductor being polished. Preferred additives contain carboxy oramino groups and are organic liquids such as polyvinyl pyrrolidone,phthalates like ammonium hydrogen phthalate and potassium phthalate andphosphates like acetodiphosphonic acid.

[0057] Typically, organic acids can be added. These acids are defined ashaving functional groups having a dissociable proton. These include, butare not limited to carboxylate, hydroxyl, sulfonic and phosphonicgroups. Carboxylate and hydroxyl groups are preferred since thesepresent the widest variety of effective organic acids. Useful acidsinclude citric acid, lactic acid, malic acid and tartaric acid.

[0058] These organic additives also can be used in polishingcompositions in which colloidal silica is the primary polishingconstituent.

[0059] In order to further stabilize the slurry against settling,flocculation and agglomeration a variety of additives such assurfactants, polymeric stabilizers, or other surface active dispersingagents may be used.

[0060] Physical, chemical and mechanical parameters all play a role inpolishing a surface. Polishing pressure is an external magnitude withwhich the polishing can be controlled and optimized. Relatively lowpolishing pressure yields an optimal result, although it is notrequired, because the particles may be prevented from being pressedthrough the encapsulating layer, created by the organic additives,during polishing.

[0061] The following examples illustrate the invention. All numbers andpercentages are on a weight basis unless otherwise specified.

EXAMPLES Example 1

[0062] This example demonstrates the ability to achieve good polishingperformance with a pad made using a gravure printing process.

[0063] Using the gravure printing process shown in FIG. 1, a sheet of 2millimeter thick polyethylene terephthalate (PET) film, precoated withan adhesion promoting coating was printed with a polishing pattern. Anaqueous based latex urethane (W242 from Witco) containing 2 weight % (40vol. %) of polymeric microballons (Expancel) was charged into tray 7. Arotogravure cylinder I etched with a polishing pattern designed for apolishing pad was used to apply the polishing layer. The roll pressureused on the impression roll 4 was 150 psi. The polishing layer was curedto form a sheet having a polishing layer having uniform pattern ofpolymeric asperities. The sheet was die cut into 28 inch diameter pad. Apressure sensitive adhesive was applied to the back of the pad andattached to a polishing machine described below.

[0064] The pad was used to polish TEOS oxide films deposited on siliconwafers. Polishing was performed on a Strasbaugh 6DS-SP using adown-force of 9 psi, platen speed of 20 rpm and a carrier speed of 15rpm. The slurry was ILD1300 from Rodel, used at a flow rate of 125mil/min. No pad conditioning was done either during polishing or betweenwafers. Wafers that were polished had excellent planarization , goodsurface appearance and excellent removal rate of material.

Example 2

[0065] This example demonstrates the ability to achieve good polishingperformance with a pad made by a screen printing process. The abrasiveis incorporated into the pad and the pad is used with a particulate-freereactive liquid to polish tungsten.

[0066] Referring to the screen printing process shown in FIG. 2, a sheetof 0-0.15 mm thick polyethylene terephthalate (PET) film 9 precoatedwith an adhesion promoting coating was used as a substrate and wasscreen printed with a filled latex formulation 11. The filled latexformulation consisted of a mixture of an aqueous based latex (VinylAcetate-Ethylene emulsion, A-460, from Air Products) and an abrasivefiller of 0.25 micron alumina. The filler loading was 75% based on dryweight of total formulation and total percent solids was 70%. Astainless steel stencil 10 was placed in intimate contact with the PETfilm. The stencil had a 79% open area, comprising hexagonal openings of6 mm hole diameter separated by 35 mil wide ribs. The filled latexformulation was applied over the stencil using a doctor blade 12. Thisforced the latex formulation material through the stencil onto the PETfilm. The resulting layer which is the polishing layer, consists ofdiscrete hexagonal regions, and was cured at 60° C. in an oven to form apolishing layer of 1 mm uniform thickness and having uniformdistribution of asperities. A pressure sensitive adhesive wassubsequently applied to the back of the PET film and the resultantpolishing pad was used to polish a tungsten film as described below.

[0067] A polishing pad was cut from the above prepared coated PET filmand attached to the polishing platen of a 12″ Leco AP-300 polishingmachine, using a down force of 7 psi, platen speed of 56 rpm and acarrier speed of 150 rpm. The pad was used in conjunction with aparticulate-free reactive liquid based on potassium iodate as theoxidizing component (MSW2000B from Rodel Inc.), used at a delivery rateof 20 ml/min. Pad concurrent conditioning was done using a 3″ 100-gritTBW diamond disc which rotated at 48 rpm. A tungsten film was polishedwith the pad and a stable 7 grams/min. removal rate of tungsten wasachieved.

[0068] In this example, the screen printing process demonstrated thefollowing major advantages over pads made according to a conventionalprocess: (1) at high filler loading, 75% and above, surface cracking ondrying in a oven was eliminated and, (2) the printing processautomatically created channels for liquid distribution across the padsurface. In conventional pad manufacturing, the above are normallycreated in subsequent, separate manufacturing steps.

[0069] Nothing from the above discussion is intended to be a limitationof any kind with respect to the present invention. For example,optionally, additional fillers such as polymeric micro-balloons may beadded to the latex formulation to control rheology and/or polishingperformance, polymer coated alumina aggregates can be used as theabrasive and the stencil can be of aluminum or plastic.

Example 3

[0070] Using the screen printing process described in Example 2, apolishing pad was produced containing 72.5% by weight of abrasiveparticle agglomerates, where the abrasive particle agglomerates comprisealumina particles held together by a polymeric binder. The resulting 24inch diameter pad was used to polish tungsten wafers using a Strasbaugh6DS-SP machine, The reactive liquid was MSW200BTM from Rodel Inc. andwas delivered at a rate of 150 ml/min. Platen speed was 80 rpm, carrierspeed was 83 rpm with a down force of 7 psi. Pad concurrent conditioningwas done using a 100-grit RESI disk at 7 psi. A tungsten removal rate of1000 to 2000A was achieved.

Example 4

[0071] Another screen printed polishing pad, similar to the onedescribed in Example 3, was used to polish copper wafers using a Westech372U polisher. The reactive liquid used was an experimental hydrogenperoxide based formulation (HR32-1) from Rodel Inc. at a delivery rateof 150 ml/min. The pad was pre-conditioned using a 100-grit TBW diamonddisk. Platen speed was 80 rpm and carrier speed was 83 rpm with a 4 psidown force. A copper removal rate of 6000 to 7000A was achieved usingpost conditioning between wafers.

Example 5

[0072] A screen printed polishing pad, similar to the one described inexample 2, was laminated to different sub-pads (SubaIV™ and DPM100™,both from Rodel Inc.), and evaluated for copper polishing using theWestech 372U polisher. The reactive liquid and polishing conditions werethe same as those used in Example 4. It was found that thecompressibility of the sub-pad significantly affected the copper removalrate, such that the more compressible the sub-pad the higher the copperremoval rate. No sub-pad, SubalV™, and DPM100™ gave removal rates of3000 to 5000A, 8000 to 9000 A, and 12,000 to 14,000 A respectively.These removal rates were achieved without post conditioning betweenwafers.

What is claimed is:
 1. A process for making polishing pads useful in themanufacture of a semiconductor device or a precursor thereto, comprisingapplying a hydrophilic polymeric polishing layer having a pattern ofpolymeric asperities to a flexible base substrate using a printingprocess.
 2. The process of claim 1 in which the hydrophilic polymericpolishing layer is a polymeric material having: i. a density greaterthan 0.5 g/cm³; ii. a critical surface tension greater than or equal to34 miliNewtons per meter; iii. a tensile modulus of 0.02 to 5GigaPascals; iv. a ratio of tensile modulus at 30° C. to tensile modulusat 60° C. of 1.0 to 2.5; v. a hardness of 25 to 80 Shore D; vi. a yieldstress of 300-6000 psi; vii. a tensile strength of 1000 to 15,000 psi;and viii. an elongation to break less than or equal to 500%,
 3. Theprocess of claim 2 in which the hydrophilic polymeric polishing layer isa polymeric material comprising at least one moiety from the groupconsisting of:
 1. a urethane;
 2. a carbonate;
 3. an amide;
 4. an ester;5. an ether;
 6. an acrylate;
 7. a methacrylate;
 8. an acrylic acid;
 9. amethacrylic acid;
 10. a sulphone;
 11. an acrylamide;
 12. a halide; 13.an imide;
 14. a carboxyl;
 15. a carbonyl;
 16. an amino;
 17. analdehydric and
 18. a hydroxyl.
 4. The process of claim 3 in which theprinting process used is gravure printing.
 5. The process of claim 3 inwhich the printing process used is screen printing.
 6. The process ofclaim 1 wherein the hydrophilic polishing layer further comprises aplurality of soft domains and a plurality of hard domains, the harddomains and soft domains having an average size of less than 100microns.
 7. A polishing pad for use in chemical mechanical polishing,comprising: a polishing layer consisting essentially of a hydrophilicpolishing layer applied by a printing process selected from the group ofgravure printing and screen printing, said polishing layer having: i.density greater than 0.5 g/cm³; ii. a critical surface tension greaterthan or equal to 34 milliNewtons per meter; iii. a tensile modulus of0.02 to 5 GigaPascals; iv. a ratio of tensile modulus at 30° C. totensile modulus at 60° C. of 1.0 to 2.5; v. a hardness of 25 to 80 ShoreD; vi. a yield stress of 300-6000 psi; vii. a tensile strength of 1000to 15,000 psi; and viii. an elongation to break less than or equal to500%.
 8. The polishing pad claim 7 in which the hydrophilic polymericpolishing layer is a polymeric material comprising at least one moietyfrom the group consisting of:
 1. a urethane;
 2. a carbonate;
 3. anamide;
 4. an ester;
 5. an ether;
 6. an acrylate;
 7. a methacrylate; 8.an acrylic acid;
 9. a methacrylic acid;
 10. a sulphone;
 11. anacrylamide;
 12. a halide;
 13. an imide;
 14. a carboxyl;
 15. a carbonyl;16. an amino;
 17. an aldehydric and
 18. a hydroxyl.
 9. A method ofpolishing a substrate of a semi-conductor device, comprising: providinga polishing pad of claim 7 and interposing a slurry of particles betweenthe semiconductor device and the pad and chemical mechanical polishingthe surface of the semiconductor device.